In the past, a liquid surface sensing device has been known that detects the liquid surface by connecting a rotational body that is pivoted by a stationary body fixed to a tank and a float that floats on the liquid surface of the liquid within the tank by an arm, and converting vertical motion of the float according to the liquid surface into rotational motion of the rotational body. As an example of such a liquid surface sensing device, in a device disclosed in Patent Document 1, when the liquid surface changes and a float moves vertically, magnets rotate, the magnetic flux density of the line of magnetic force passing through a magnetoelectric conversion element changes, and an electric signal corresponding to it is outputted. Also, because the device disclosed in Patent Document 1 can reduce the shift of the relative position between the magnets and the magnetoelectric conversion element by elastically deforming elastic claws and pressing in the magnets, the detection accuracy of the liquid surface based on the sensing result of the magnetic flux density of the magnets is high.